LEDs are diodes capable of emitting light when forward biased. They are light-emitting devices manufactured by semiconductor materials mostly including III-V chemical elements, such as gallium phosphide or gallium arsenide in the early days and aluminum-gallium-indium phosphide or gallium-indium nitride for high-brightness LEDs at present day. The light-emitting principle is to apply a current to the compound semiconductor. Then part of the energy will be released in the form of light via recombination of electrons and holes and thus achieving light-emitting effect.
Because the used materials are different, the energy levels of electrons and holes in LEDs differ. When the electrons and holes recombine, the released photons will hence have different energies, resulting in light with different wavelengths, which are light with different colors such as red, orange, yellow, green, blue, or invisible light.
Different from earlier light sources, LEDs are luminescent with low power consumption, long lifetime, no warm-up time, fast response, and small size. Besides, they are vibration tolerant, suitable for mass production, and easy to be manufactured extremely small or in arrays according to requirements of applications. Currently, LEDs are widely applied to indicators and displays of information, communication, and consumer electronic products, and thereby they have become indispensable important devices in daily lives.
As the LED technology becomes increasingly mature, its application areas are becoming wider. In the residence area, the applications include wall lamps, night lamps (the requirement in brightness for this application is not high, and thereby is the earliest application of LEDs), auxiliary lighting, garden lamps, and reading lamps. In the equipment area, the applications include emergency indicators and hospital bed lamps. In the store area, their applications include spotlights, embedded lamps, barrel lamps, and light bars. In the outdoor applications, LEDs can be used to decorate the appearance of buildings and used in solar-energy lamps. In addition, they can also applied to light shows.
The lighting market is long considered as the greatest and potential market of LEDs, even though no major lighting product is proposed owing to cost and performance limitations. However, it is undeniable that LED technology has been developing rapidly in recent years, making it to occupy some market in the special light market, such as the niche markets of freezer lighting, aviation lamps, or traffic lights). In the general lighting market, including barrel lamps, embedded lamps, spotlights, and landscape lighting products, some products start to replace traditional light sources such as halogen lamps or incandescent lamps.
At present, a heat dissipating structure is disposed below the LED module in an LED streetlight. It is because LEDs generate a huge amount of heat. If no heat dissipating structure is disposed, the lifetime of the LED module can be very possibly reduced owing to overheating. Besides, the lifetime of the power supply of the LED streetlight can be also substantially reduced caused by long-term overheating applications, and hence leading to frequent replacement of power supplies. Moreover, the lighting angle and direction of current LED streetlight are fixed, and therefore they cannot be adjusted according to the environment during installation.
Accordingly, the present invention provides an LED streetlight structure, which has a heat dissipating structure at the power supply and has a angle adjusting structure for the lamppost for improving heat dissipation of the power supply and changing the lighting angle and direction of the LED streetlight structure.